/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.servlet.mvc.method.annotation;

import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.security.Principal;
import java.time.ZoneId;
import java.util.Locale;
import java.util.TimeZone;

import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import javax.servlet.http.PushBuilder;

import org.springframework.core.MethodParameter;
import org.springframework.http.HttpMethod;
import org.springframework.lang.Nullable;
import org.springframework.util.ClassUtils;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;
import org.springframework.web.multipart.MultipartRequest;
import org.springframework.web.servlet.support.RequestContextUtils;

/**
 * Resolves request-related method argument values of the following types:
 * <ul>
 * <li>{@link WebRequest}
 * <li>{@link ServletRequest}
 * <li>{@link MultipartRequest}
 * <li>{@link HttpSession}
 * <li>{@link PushBuilder} (as of Spring 5.0 on Servlet 4.0)
 * <li>{@link Principal}
 * <li>{@link InputStream}
 * <li>{@link Reader}
 * <li>{@link HttpMethod} (as of Spring 4.0)
 * <li>{@link Locale}
 * <li>{@link TimeZone} (as of Spring 4.0)
 * <li>{@link java.time.ZoneId} (as of Spring 4.0 and Java 8)
 * </ul>
 *
 * @author Arjen Poutsma
 * @author Rossen Stoyanchev
 * @author Juergen Hoeller
 * @since 3.1
 */
public class ServletRequestMethodArgumentResolver implements HandlerMethodArgumentResolver {

    @Nullable
    private static Class<?> pushBuilder;

    static {
        try {
            pushBuilder = ClassUtils.forName("javax.servlet.http.PushBuilder",
                    ServletRequestMethodArgumentResolver.class.getClassLoader());
        } catch (ClassNotFoundException ex) {
            // Servlet 4.0 PushBuilder not found - not supported for injection
            pushBuilder = null;
        }
    }


    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        Class<?> paramType = parameter.getParameterType();
        return (WebRequest.class.isAssignableFrom(paramType) ||
                ServletRequest.class.isAssignableFrom(paramType) ||
                MultipartRequest.class.isAssignableFrom(paramType) ||
                HttpSession.class.isAssignableFrom(paramType) ||
                (pushBuilder != null && pushBuilder.isAssignableFrom(paramType)) ||
                Principal.class.isAssignableFrom(paramType) ||
                InputStream.class.isAssignableFrom(paramType) ||
                Reader.class.isAssignableFrom(paramType) ||
                HttpMethod.class == paramType ||
                Locale.class == paramType ||
                TimeZone.class == paramType ||
                ZoneId.class == paramType);
    }

    @Override
    public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
            NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {

        Class<?> paramType = parameter.getParameterType();

        // WebRequest / NativeWebRequest / ServletWebRequest
        if (WebRequest.class.isAssignableFrom(paramType)) {
            if (!paramType.isInstance(webRequest)) {
                throw new IllegalStateException(
                        "Current request is not of type [" + paramType.getName() + "]: " + webRequest);
            }
            return webRequest;
        }

        // ServletRequest / HttpServletRequest / MultipartRequest / MultipartHttpServletRequest
        if (ServletRequest.class.isAssignableFrom(paramType) || MultipartRequest.class.isAssignableFrom(paramType)) {
            return resolveNativeRequest(webRequest, paramType);
        }

        // HttpServletRequest required for all further argument types
        return resolveArgument(paramType, resolveNativeRequest(webRequest, HttpServletRequest.class));
    }

    private <T> T resolveNativeRequest(NativeWebRequest webRequest, Class<T> requiredType) {
        T nativeRequest = webRequest.getNativeRequest(requiredType);
        if (nativeRequest == null) {
            throw new IllegalStateException(
                    "Current request is not of type [" + requiredType.getName() + "]: " + webRequest);
        }
        return nativeRequest;
    }

    @Nullable
    private Object resolveArgument(Class<?> paramType, HttpServletRequest request) throws IOException {
        if (HttpSession.class.isAssignableFrom(paramType)) {
            HttpSession session = request.getSession();
            if (session != null && !paramType.isInstance(session)) {
                throw new IllegalStateException(
                        "Current session is not of type [" + paramType.getName() + "]: " + session);
            }
            return session;
        } else if (pushBuilder != null && pushBuilder.isAssignableFrom(paramType)) {
            return PushBuilderDelegate.resolvePushBuilder(request, paramType);
        } else if (InputStream.class.isAssignableFrom(paramType)) {
            InputStream inputStream = request.getInputStream();
            if (inputStream != null && !paramType.isInstance(inputStream)) {
                throw new IllegalStateException(
                        "Request input stream is not of type [" + paramType.getName() + "]: " + inputStream);
            }
            return inputStream;
        } else if (Reader.class.isAssignableFrom(paramType)) {
            Reader reader = request.getReader();
            if (reader != null && !paramType.isInstance(reader)) {
                throw new IllegalStateException(
                        "Request body reader is not of type [" + paramType.getName() + "]: " + reader);
            }
            return reader;
        } else if (Principal.class.isAssignableFrom(paramType)) {
            Principal userPrincipal = request.getUserPrincipal();
            if (userPrincipal != null && !paramType.isInstance(userPrincipal)) {
                throw new IllegalStateException(
                        "Current user principal is not of type [" + paramType.getName() + "]: " + userPrincipal);
            }
            return userPrincipal;
        } else if (HttpMethod.class == paramType) {
            return HttpMethod.resolve(request.getMethod());
        } else if (Locale.class == paramType) {
            return RequestContextUtils.getLocale(request);
        } else if (TimeZone.class == paramType) {
            TimeZone timeZone = RequestContextUtils.getTimeZone(request);
            return (timeZone != null ? timeZone : TimeZone.getDefault());
        } else if (ZoneId.class == paramType) {
            TimeZone timeZone = RequestContextUtils.getTimeZone(request);
            return (timeZone != null ? timeZone.toZoneId() : ZoneId.systemDefault());
        }

        // Should never happen...
        throw new UnsupportedOperationException("Unknown parameter type: " + paramType.getName());
    }


    /**
     * Inner class to avoid a hard dependency on Servlet API 4.0 at runtime.
     */
    private static class PushBuilderDelegate {

        @Nullable
        public static Object resolvePushBuilder(HttpServletRequest request, Class<?> paramType) {
            PushBuilder pushBuilder = request.newPushBuilder();
            if (pushBuilder != null && !paramType.isInstance(pushBuilder)) {
                throw new IllegalStateException(
                        "Current push builder is not of type [" + paramType.getName() + "]: " + pushBuilder);
            }
            return pushBuilder;

        }
    }

}
